Efficient production of magnesium silicide from elemental powders by combustion synthesis

Abstract A facile method for efficient synthesis of magnesium silicide by the implementation of combustion reactions in compressed, elemental mixtures of magnesium and silicon was developed. The exothermic reaction between Mg and Si was initiated using an induction-activated method which allowed rapid, simultaneous preheating and ignition of the samples under an argon gas atmosphere and resulted in the establishment and propagation of an exothermic reaction front throughout the samples. The synthesis was accomplished in very short times and the products were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. The effect of such parameters as sample green density and Si particle size on the combustion temperature, ignition time, and phase evolution of the products was evaluated. It was found out that a decrease in Si particle size and an increase in sample green density favor the reaction kinetics and minimize the formation of undesirable phases. The reaction front velocities were calculated by recording the temperature histories of two spaced points within the samples and used to determine the activation energy of the reaction. The calculated value of the activation energy for the self-propagating, high-temperature synthesis (SHS) of Mg2Si was ∼195 kJ mol−1.